1. How about 6 of these in a 2x2 space?
2. I wonder about color temperature. I feel that hans and area 51 have spent a lot of time maximizing the colors.
3. As suggested it would seem that the spots would be better than regular shaped bulbs. Do you agree?
1. That would be 28w/sq ft. That would be good. I just like to distribute the light a little more. The 9.5w bulbs can get closer which is good for the sides. If you had one in each corner, that would be 38w from four angles. If you used an extra 2 floods on top it would make the top a little crowded.
(I don't think you could put the floods on the sides because you need a little more distance. I suppose you could do 2 floods on top and 4 spots, each one hitting at an angle from the top corner. This would give you some top and some sidelight. The throw of the spot would give sidelight. But, if the plant became larger than expected you'd run the risk of it being too close to the spots. I think I bleached the plant I posted a picture of. When it stretched I wasn't paying attention to the focus of the spots. It got a little pale on top. In the past I've struggled with mg def and also reducing N too quickly. I'm not sure if the early yellowing was due to that or the light being too close. But, it's something to be careful of with the spots because they are intense. I intended to use floods. I started with spots to see how they worked. Then decided I shouldn't change things and be unsure of actual performance from the grow. That's also the reason I haven't added lights to get higher than 19w/sq ft. I want a clear result.).
2. I don't think our plants are as sensitive to spectrum as we believe. However, using 9.5w bulbs for sidelighting would give you some control over the color temperature. You could use 5k in veg, 2.7k in flower. The top floods would always be 3k. (You could incrementally turn those on in veg as the plant grows. Maybe end up with 2 floods and 4 5k sidelights at the end of veg, then 4 floods and 4 2.7k sidelights at the end of flower.
3. I think floods are better than spots unless you're in a tall space. (I'm not sure spots are better in a tall space, just that you need more vertical height to focus them.).
Omnidirection lightbulbs are ok. It's just that you have to add your own reflector to make use of the light. That's an added initial expense. But, you pay for that with integral spots/floods. An omni is about $7, while a spot/flood is $20.
Either way, you're starting with 90-100 lumens per watt from the diode. The reflector (whether added or built-in) points that light in a certain direction -- but at a loss of lumens. This can be confusing when you look at an omni which says it has more lumens compared to the same wattage spot/flood. If you add a reflector to the omni you'll have similar actual lumens.
FWIW: That's another reason I want to try SMD5037 strip light. Point it directly at the plant. No need to make it look like a traditional light (reflected omnidirectional energy). 12 volts, so there's no need to keep it behind glass or a lens for safety reasons. I think it could be better suited. But, I don't know yet.